阴离子交换树脂对茶氨酸的吸附动力学和热力学

以酶法制备茶氨酸,研究了碱性条件下阴离子交换树脂对茶氨酸的吸附与分离. 结果表明,强碱性树脂对茶氨酸的吸附性能优于弱碱性树脂,且其吸附容量受pH值的影响较小,pH=9.0时凝胶型强碱性树脂HZ202对茶氨酸的平衡吸附量可达96.3 mg/g. 对HZ202吸附茶氨酸的吸附等温模型及动力学、热力学参数进行了分析,结果表明,茶氨酸在HZ202树脂表面为非均一分布,Spis模型可较好模拟其吸附等温线数据;热力学参数计算结果显示,不同温度下吸附过程的吉布斯自由能变DG均为负值,表明吸附为自发的放热过程;吸附过程的焓变DH=20.9~418.4 kJ/mol,可判断其为化学吸附. 茶氨酸吸附过程符合准二级动力学方程,吸附过程受化学反应控制,提高茶氨酸初始浓度可提高吸附速率.     

壳聚糖-单糖美拉德反应产物的制备及其在抗菌和抗氧化中的应用研究进展

为了对美拉德反应体系进行综合评价以及优化茶氨酸-葡萄糖美拉德反应条件,本研究构建了茶氨酸-葡萄糖美拉德反应综合评价值的人工神经网络耦联遗传算法（BP-GA）模型,优化得到了最佳反应条件。先通过熵值法求出荧光值、A₂₉₄、A₄₂₀、葡萄糖及茶氨酸剩余量五个评价指标之间的权重,再结合单因素实验及正交试验结果,建立输入为实验因素参数,输出为美拉德反应综合评价值的BP-GA人工神经网络模型,最后使用建立好的模型得到茶氨酸-葡萄糖美拉德反应的最优条件及相应的美拉德反应综合评价值。结果表明,通过建立的BP-GA模型进行全局优化得到茶氨酸-葡萄糖美拉德反应的最优条件为：反应温度117.6 ℃,反应时间1.8 h,pH7.3,羰基氨比1:2,此条件下美拉德反应的综合评价值为93.22。经过与正交试验得到的结果比较,发现BP-GA模型具有良好的预测性能。利用BP-GA模型,本研究得到了模型美拉德反应的最优条件,这将为美拉德反应模拟体系的构建及反应的预测提供参考。

     

L-谷氨酰肼为底物酶法制备茶氨酸

采用一种廉价的底物L-谷氨酰肼代替L-谷氨酰胺,成功地合成了茶氨酸,并且对该酶促反应的条件进行了初步优化。结果表明,以L-谷氨酰肼为底物时,γ-谷氨酰转肽酶(GGT)活性约是以L-谷氨酰胺为底物时的78.3%。该酶促反应的最适条件为:pH=10,反应温度40℃,n(L-谷氨酰肼)∶n(乙胺)=1∶10,L-谷氨酰肼初始浓度0.3mol/L。利用以上条件进行了茶氨酸的小量制备,投料L-谷氨酰肼50g,乙胺140g,反应40h,L-谷氨酰肼的摩尔转化率达84.1%,经离子交换树脂分离产物,得到31.8g高纯度茶氨酸。该结果显示良好应用前景。     

Optimising the extraction of tea polyphenols, (−)‐epigallocatechin gallate and theanine from summer green tea by using response surface methodology

In this study, response surface methodology was applied to determine the optimal conditions for the extraction of tea polyphenols, EGCG and theanine from summer green tea. As results, the optimal extraction conditions were determined to be temperature 96 °C, time 40 min and ratio of water to raw material 16 mL g^?1. Under these optimal conditions, the experimental values for tea polyphenols, EGCG, theanine and IC₅₀ for DPPH free radical scavenging activity were 133.41 ± 3.12 mg gallic acid g^?1, 30.23 ± 1.22, 3.99 ± 1.13 mg g^?1 and 724.95 ± 15.12 μg mL^?1, respectively. There was no statistical difference at significant level of 0.05 between the experimental and predicted values. The results suggested that the regression models were accurate and adequate for the bioactives extraction from summer green tea.     

Magnesium nutrition on accumulation and transport of amino acids in tea plants

BACKGROUND: Free amino acids in young tea shoots are important chemical constituents, remarkably influencing the quality of green teas. Nutrient solution, soil pot and field experiments were conducted to investigate the effect of magnesium nutritional status on accumulation and transport of free amino acids in tea plants ( Camellia sinensis (L.) O. Kuntze). RESULTS: A sufficient supply of Mg in nutrient solution increased biomass production and concentrations of free amino acids, notably theanine in young shoots and roots, without affecting total N in the leaves, absorption rates of inorganic N and glutamine synthetase activity. Amino acids in xylem saps and phloem exudates or total sugars in phloem exudates of tea plants from pot and field experiments showed their highest levels in bud breaking and shoot extension in early spring (March and early April). Application of Mg increased the amounts of amino acids and total sugars in the xylem saps and phloem exudates. CONCLUSION: Adequate supply of Mg nutrient promoted the synthesis of theanine in roots and its accumulation in the young shoots of tea plants. Magnesium nutritional status was an important factor influencing the mobility of amino acids and sugars via xylem and phloem especially when N and C reserves remobilized to support spring growth of young shoots. Copyright © 2011 Society of Chemical Industry     

表面活性剂双水相分离茶多酚生产废液中的茶氨酸(英文)

Extraction of theanine from waste liquid of tea polyphenol production was studied in aqueous surfactant two-phase system (ASTP) with cationic surfactant (CTAB) and anionic surfactant (SDS). Results indicate that the region of ASTP is narrow and there is only a two-phase region of cationic surfactant. The increase in concentrations of NaBr and Na2SO4 are beneficial to the formation of ASTP. Theanine concentration in the bottom phase increases with increasing concentration of theanine, whereas the partition coefficient and extraction rate only change a little when the concentration of theanine is above 0.2 g·L-1 . With the increase of SDS concentration, the phase ratio and the partition coefficient decrease, while the extraction efficiency of theanine increases and the concentration of theanine changes a little in the range from 2.4/7.5 to 2.8/7.2 for SDS/CTAB ratio. The temperature has a notable effect on the concentration of theanine in the bottom phase, partition coefficient and extraction rate of theanine. The increase of waste liquid decreases the phase ratio, increases the concentration and extraction rate of theanine in the bottom phase, since the protein and the saccharide enter the bottom phase with theanine.     

毛细管区带电泳法测定茶叶中咖啡因、茶氨酸、表儿茶素和表没食子儿茶素没食子酸酯

目的：建立毛细管区带电泳法测定茶叶中咖啡因、茶氨酸、(－)表儿茶素(EC)和(－)表没食子儿茶素没食子酸酯(EGCG)含量的分析方法。方法：以含有20mmol/L硼砂和磷酸盐(pH9.5)为电泳介质,在电压25kV、柱温25℃条件下分离和210nm波长处检测。结果：在8min内可将4种待测组分全部分离且各组分的质量浓度与峰面积呈良好的线性关系,相关系数r为0.9944～0.9995,检测限为0.001～0.01μg/mL,各组分的加标回收率为89.98%～102.7%,相对标准偏差小于9.11%。结论：本实验建立的方法直接用于茶叶中咖啡因、茶氨酸、EC和EGCG的测定,结果满意。     

Effect of root zone pH and form and concentration of nitrogen on accumulation of quality‐related components in green tea

Green tea quality is greatly influenced by concentrations of free amino acids, polyphenols (mainly catechins) and caffeine. The present study investigated the principal relationship between selected nutritional factors (form and concentration of N supply, root zone pH) and accumulation of these quality‐related components of tea (Camellia sinensis (L.)) plants. Tea plants were hydroponically cultured with NH , NO and NH NO at pH 4.0, 5.0 and 6.0 in one experiment and supplied with varying N concentrations (0.75, 2.0 and 4.5 mmol L^?1, NH /NO^?₃ = 3:1) in another experiment. Concentrations of free amino acids were considerably higher in NH ‐ than in NO ‐fed plants. This was attributed to the much greater absorption of NH compared with NO . Furthermore, the relative allocation of absorbed N to free amino acids, particularly theanine and glutamine, was substantially increased by NH nutrition, suggesting that NH was more readily assimilated than NO into theanine. The concentration of caffeine was increased in NH ‐ and (NH NO )‐supplied plants, whereas concentrations of catechins were reduced in (NH NO )‐fed plants. Root zone pH did not influence concentrations of most free amino acids in young shoots, with the exception of theanine, which increased at low pH (4.0) irrespective of N form; this likely stemmed from an accumulation effect, as growth decreased more strongly than N absorption. Raising the N supply increased plant N allocation to free amino acids. The increase was most striking for arginine, while theanine was only marginally affected. This may have adverse consequences for green tea quality, as less favourable taste characteristics have been attributed to arginine. Copyright © 2007 Society of Chemical Industry     

几种激素对茶愈伤组织合成茶氨酸的影响

根据生长素（ＩＡＡ），吲哚丁酸（ＩＢＡ），萘乙酸（ＮＡＡ），以及２，４－二氯苯氧乙酸（２，４－Ｄ）和６－卞艹基腺嘌呤（６－ＢＡ），激动素（ＫＴ），玉米素（ＺＴ）及三十烷醇（ＴＡ）等的不同浓度和不同组合，测定茶愈伤组织生长和茶氨酸的积累情况，以求得茶愈伤组织生长和茶氨酸积累的较佳培养条件。试验证明，以４ｍｇ／Ｌ６－ＢＡ＋２ｍｇ／ＬＩＡＡ或３ｍｇ／Ｌ６－ＢＡ＋１．５ｍｇ／ＬＩＡＡ＋２ｍｇ／ＬＴＡ的组合，添加于ＭＳ培养基上，茶愈伤组织生长和茶氨酸积累均良好，茶氨酸含量最高可达１７０ｍｇ／ｇ．     

一种酸枣仁提取物、茶氨酸、γ-氨基丁酸配方产品改善睡眠作用研究

目的:探讨一种酸枣仁提取物、茶氨酸、γ-氨基丁酸配方产品改善睡眠作用。方法:180只健康雄性Balb-c小鼠按体重随机分为三个大组,每个大组60只小鼠分别随机分为空白对照组和低、中、高3个剂量组,每组15只。酸枣仁提取物、茶叶茶氨酸和GABA配方产品按照低、中、高3个剂量(95、190、285 mg/kg·bw)通过直接睡眠、延长戊巴比妥钠睡眠时间、戊巴比妥钠阈下催眠剂量和巴比妥钠睡眠潜伏期实验,研究酸枣仁提取物、茶氨酸、γ-氨基丁酸复合配方对小鼠睡眠的影响。结果:酸枣仁提取物、茶氨酸与γ-氨基丁酸配方产品无直接催眠作用。与对照组相比,低、中、高剂量组小鼠戊巴比妥钠睡眠时间分别延长14.53%、17.12%、23.80%,且差异均具有统计学意义(P<0.05)。各剂量组小鼠30 min内小鼠阈下剂量实验均为阳性,小鼠睡眠发生率增加,差异具有统计学意义(P<0.05)。各剂量组小鼠巴比妥钠睡眠潜伏期时间分别缩短12.48%、24.19%、24.07%,差异有统计学意义(P<0.05)。结论:酸枣仁提取物、茶氨酸、γ氨基丁酸配方产品具有缩短小鼠睡眠潜伏期,延长小鼠睡眠时间,同时增加小鼠入睡发生率的作用,具有改善睡眠的功效。